FIG. 1A illustrates a process control system 100 of an industrial plant for oil, steel and chemical process industries. In the industrial plant, field devices such as sensors 102 and valve devices, actuators 104 measure or control processes such as fluid process performed by plant equipment. Examples of sensors 102 are flowmeters, temperature indicators, valve devices 104 are flow amount control valves and open/close valves, actuators 104 are fans and motors. The field devices 102, 104 are connected to a field network 106. The field devices 102, 104 are connected through input-output (I/O) units to controllers 108 which are in a control network 110. Based on measurements from the sensors 102, the controllers 108 perform computations which are used to generate signals to control the actuators. Each control logic in the controller 108 is encapsulated in a function block. The function block is defined to receive or generate input, output parameters defined for each field device and include algorithms to calculate the parameters. Parameters include process variables and tuning parameters which are generated in the function block. Process variable is variable for which a measurement exists, such as temperature, pressure, force, feed, flow rate, chemical composition, weight, position and speed. Tuning parameter is a variable applied in the controller to control the processes. Control logic is an algorithm of the controllers 108.
Human machine interface (HMI) terminals 112 in the control network 110, exchange data with the function blocks and provide information to operators for operating the process control system 100. The process control system 100 manages and issues commands, from the function blocks, for parts such as equipment and field devices based on the exchanged data. The issued commands are based on control logic which is prepared and modified in an engineering tool 120 according to design data, which is a specification of the industrial plant. The control logic is converted to binary control data for execution in the controllers and HMI terminals. The operators control and operate the industrial plant by applying the binary control data in the controllers and HMI terminals. The HMI terminals 112 screen definitions are prepared by the engineering tool 120. The function blocks, based on the measurements from the sensors and binary control data, perform computation to generate signals for the actuators. The operators set a design value for the tuning parameters during process tuning.
FIG. 1B illustrates the engineering tool 120 for setting or configuring the process control system 100. Users use an editor 122 in the engineering tool 120 to prepare and modify the control logic for any change in the design data of the industrial plant. Example of a change is to set a different field device parameter value for a different process or a different raw material for the process. The different process is for a different product or a different grade of a same product. The prepared and modified control logic is stored as serialized control data 124. The serialized control data 124 is read by a converter 126. The converter 126 generates, from the serialized control data 124, binary control data 128 which is control data in binary format. The binary control data 128 is stored in a database 130. The binary control data 128 is sent to process control system 100 for execution in the HMI terminals 112 and controllers 108.
In the industrial plant, there are many data files and data sets for the parameters. The parameters have complex data relationships when related data sets are of different type or source. An example is a parameter in a function block related to a controller. The parameter is defined as a first type in the function block and defined as a second type when in an alarm management system. The first type and second type of definitions are different. It is tedious to identify corresponding parameters to be updated in the control logic for the process control system 100 when a parameter or parameter relationship is changed in the design data.
Documents, such as instruction manuals, control logic definitions, and specifications, for the industrial plant are prepared manually as shown in FIG. 1C, using a tool which is separate and different from the engineering tool. The documents for the process plant, from the control logic to the control data, are prepared independently.
Since the documents are prepared manually, it is tedious and time-consuming to ensure that the documents are consistent with the control logic or control data for the industrial plant. In an example of an oil process plant, composition of raw materials such as oil depends on country of origin. Therefore, control logic in process control system of the process plant has to be changed for each different composition. Documents for the different control logic for the different composition of raw materials are manually prepared individually. The preparation is tedious and time consuming.
The documents are prepared by a user, who is either a customer or a vendor, of the engineering tool or process control system. As different users prepare and modify the control logic differently, the documents must be prepared or updated by the same user. This is inconvenient and cumbersome to other users.
Further, the control logic is changed continuously due to continuous operational improvements in the industrial plant. In an ideal situation, the documents are updated for every change in the control logic. However, in reality, it is logistically challenging to update the documents every time there is a change in the control logic. Therefore, the documents are usually not updated. In some cases, users consolidate changes in the control logic to update the documents periodically. Mistakes and oversights are common occurrences during the preparation or update of the documents, since documentation is a manual process. The periodic update can cause more inaccuracies. This results in inconsistency between the control logic and the documents. When the documents lack accuracy, the documents are not reliable documentation for the process plant.
In a typical industrial plant, a specification document consists of thousands of pages. It is tedious and time-consuming to update such a huge document manually. In order to ensure that the documents are consistent with the control logic, a lot of additional man-effort, time and cost are required for the manual process. This increases the cost to maintain and update the process control systems. In addition to the cost of maintenance and update of the control logic, an additional cost is required to ensure that the documentation is consistent with the control logic, when a change is required for the process control system. In a cost competitive environment for process industries, the cost to maintain documentation is put off or avoided completely. In these situations, the documents are obsolete from a lack of update. There is a need to improve the preparation and update of the documents.
Industrial plants are designed and built to last for a long period of 30 years or more. In a typical large scale industrial plant, the process control system controls more than 10,000 field devices. There are many complex and advanced functions in the process control system. For an industrial plant which has many complex and advance functions, many users are required to work together to maintain or update control logic of the plant control system. The users would have been changed over the years of plant operation. Existing users have to refresh their understanding on the control logic, and new users have to find out and understand the control logic, in order to make changes to the control logic. One way to understand the control logic is from the documents. It is not possible to understand from the documents when the documents are inconsistent with the control logic due to the reasons explained above.
There are many engineering tasks to prepare a process control system. One engineering task is a method of generating the control logic or the document. Tests are performed on the generated control logic to ensure that the control logic is correct. Engineering tasks, design, generation and testing of control logic, are performed repetitively since the control logic includes data specific to each controller 108. This requires a lot of effort and time to prepare the process control system 100 for the industrial plant.
Different users perform engineering tasks differently. More effort is required from the user who does the maintenance when the user is different from a previous user. There is a need to improve and standardize the quality of engineering tasks. This is to improve the ease of understanding the process control system of the process plant.
The users have to spend additional man-effort and time to decipher the control logic and verify using different types of document, such as specification documents with all revision changes. This incurs additional cost for the maintenance of the process control system.
There is a need to improve the efficiency to prepare, modify and maintain a process control system and its documentation by reduction of the man-effort, time and cost involved. Further, the consistency of the control logic and the documentation needs to be improved. There needs to be a mechanism to enable continuous maintenance and operational improvements efficiently.